Axial bearing device

ABSTRACT

This invention relates to a thrust bearing arrangement in which a thrust bearing (17, 18) is brought to a given position on an axle or shaft (15, 16) and secured firmly in this position by means of a locking ring (23, 24) capable of being displaced along the axle or shaft. In order to enable this arrangement to be achieved quickly and easily, the locking ring has the form of a shrink ring (23, 24) which is heated to an appropriate temperature and then slid along a smooth part of the axle (15, 16). The shrink ring is dimensioned so that it will shrink firmly around the axle (15, 16) when cooled to normal operating temperature, so as to be immovable on the axle when subjected to axial forces occurring in operation. The thrust bearing (17, 18) is positioned, according to the invention, in a bearing seating, which enables the transverse insertion of a feeler gauge or corresponding device to provide a given clearance at a selected end of the bearing (17, 18) prior to shrink fitting the locking ring (23, 24).

BACKGROUND OF THE INVENTION

The present invention relates to a thrust bearing arrangement, in whicha thrust bearing is brought to a given position on an axle or a shaftand subsequently secured in said position.

Normally, a thrust bearing is moved to a given setting or position on anaxle and secure preliminary in this position by means of washers, shimsor like devices, whereafter a locking ring is screwed along the axleinto locking abutment with the bearing. This procedure, however, ishighly time consuming and also assumes that the setting of the thrustbearing can be checked in some way or another.

The object of this invention is to provide a thrust bearing arrangementof the aforesaid kind which will enable the thrust bearing to be broughtto a given position or setting on an axle and quickly secured in saidposition in a simple manner.

SUMMARY OF THE INVENTION

According to the present invention, a specific clearance is set betweenan end wall of a rotor and an inner surface of a high pressure end wallof a screw rotor compressor while mounting an axle of said rotor in athrust bearing in a bearing seating in said high pressure end wall byproviding the high pressure end wall of the screw rotor compressor withan access space to provide radial access to the bearing seating; andtransversely inserting a feeler gauge in the radial access space at oneor another end surface of the thrust bearing. The rotor is into abutmentwith the inner surface of the high pressure end wall; a separate heatedshrink ring is pushed over the axle of the rotor and pressed against thethrust bearing with the feeler gauge still in position in the radialaccess space at an end surface of the thrust bearing; and then thefeeler gauge is removed after shrink ring has cooled down.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawing, the single FIGURE of which illustrates inlongitudinal section a screw compressor provider with a thrust bearingarrangement according to one embodiment of the invention.

DETAILED DESCRIPTION

The illustrated screw compressor comprises a housing 1 whichincorporates a high-pressure end wall 2. An end wall 3 is screwed firmlyonto the low pressure side and the high-pressure end wall 2 carries acasing 4. A male rotor 5 and a female rotor 6 are rotatably journalledin the housing 1, in radial bearings 7.

The rotors 5, 6 are provided on the high pressure side with respectivebearing trunnions 15, 16 which extend externally beyond thehigh-pressure end wall 2. A respective thrust bearing 17, 18 is mountedon each of the outwardly projecting trunnions 15, 16. Each of the thrustbearings comprises a rolling bearing having a respective inner race 19and 20, which is slideably mounted on a respective trunnion 15, 16, andan outer race 21 and 22 which abut the outer surface of the end wall 2.A locking ring 23 and 24 is shrink-fitted on a respective trunnion inabutment with a respective inner race 19 and 20.

All play, or clearance, between the shrink rings 23, 24, the thrustbearings 17, 18 and the outer surface of the end wall 2 is eliminatedwhen the rotors 5, 6 are urged in a direction towards the low-pressureend wall 3, while an intended clearance a of 0.04-0.05 mm is obtainedbetween the inner surface of the end wall 2 and the high-pressure endsurfaces of the rotors 5, 6 when the shrink rings 23, 24 are locked tothe trunnions 15, 16 in precisely the correct position.

This thrust bearing arrangement to produce the above results is achievedquickly and easily, by simply displacing the rotors 5, 6 into abutmentwith the inner surface of the high-pressure end wall 2, prior to fittingthe shrink rings, by appropriate manipulation of the low pressuretrunnions, to which access could be obtained via a belt pulley 25mounted on the low pressure trunnion 26 of the male rotor 5 and byremoving a cover plate 27 outside the low pressure trunnion 28 of thefemale rotor.

Casing 4 is removed from the high-pressure end wall 2 to provide anaccess space for a feeler gauge or the like. A feeler gauge, orcorresponding device, whose thickness corresponds to the intendedclearance a is then inserted between respective outer races 21, 22 andthe outer surface of the high-pressure end wall 2. This could be readilycarried out, since the thrust bearings 17, 18 are not yet secured inposition. Heated shrink rings 23, 24 are then pushed over respectivetrunnions 15, 16 and pressed against the outer surfaces of respectiveinner races 19 and 20. As the shrink rings 23, 24 cool, they shrinkfirmly around the trunnions 15, 16 and therewith fix the clearance a.

It will be understood that the invention is not restricted to theillustrated and described embodiment and that modifications can becarried out within the concept of the invention. For example, theinvention may be applied with other types of thrust bearings.Furthermore, an enhanced temperature differential can be achieved whenfitting the shrink rings 23, 24, by forced cooling of the trunnions 15,16.

I claim:
 1. A screw rotor compressor in which a specific clearance canbe set between an end wall of a rotor and an inner surface of a highpressure end wall of the screw rotor compressor, comprising:a bearingseating in said high pressure end wall for receiving a thrust bearing;said rotor of said compressor having an axle portion which extendsexternally beyond an outer surface of said high pressure end wall; athrust bearing mounted on said externally extending axle and received insaid bearing seating; means at said high pressure end wall of said screwrotor compressor for defining an access space to provide radial accessto said bearing and bearing seating; a feeler gauge transverselyinsertable in said radial access space at one or another end surface ofsaid thrust bearing; wherein said rotor is displaced into abutment withsaid inner surface of said high pressure end wall; a separate heatedshrink ring which is mounted over said axle of said rotor with saidthrust bearing interposed between said heated shrink ring and said highpressure end wall, said heated shrink ring being pressed against saidthrust bearing with said feeler gauge still in position in said radialaccess space at said one or said another end surface of said thrustbearing; and wherein said feeler gauge is removed after said shrink ringhas cooled down, said shrink ring shrinking and being thereby fixed tosaid rotor axle when cooled down.
 2. The apparatus of claim 1, whereinsaid thrust bearing has an end surface which faces said high pressureend wall, and wherein said feeler gauge is inserted between the outersurface of said high pressure end wall and said thrust bearing endsurface which faces said high pressure end wall.
 3. The apparatus ofclaim 1, wherein said thrust bearing has inner and outer races, andwherein said feeler gauge is inserted between said outer race and theouter surface of said high pressure end wall.